According to C object A and C1 are co-moving and objects B and C2 are also co-moving.
Object C can ascertain that C1 and C2 are pulsing in phase, in other words they share the same tick rate. He also knows that A and B are also in phase.
Object C can clearly see that the same would apply for objects A and B.

Now this is where it gets sticky.

Object A and object B are unaware of C, C1 and C2.

Object A according to SRT will state that object B has all the velocity thus his light pulses on his reflector [remember the two ship scenario posted earlier] will be out of phase.

Now clearly there is a conflict between what C knows as true and A and B know as true.

The question is : Who is correct? Is C correct? Or is either of A or B correct?

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another are I have jsut thougth of that may lead SRt astray is that even if a GPS has supposedly got >V than a surface clock it's orbit may actually be slower than that of the surface due to the movement of teh solar system within the galactic ballet.

In other words the illusion of greater velocity could give totally wrong dilation results.

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Now clearly there is a conflict between what C knows as true and A and B know as true.

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Yes there is and this is not a problem.

The question is : Who is correct? Is C correct? Or is either of A or B correct?

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There is no absolute truth. Reality is subjective and always has been. It just gets a bit more confusing when the oddities of light are thrown in. Each is correct IN THEIR OWN FRAME. If a kid hits a baseball and I'm 1000ft away and you're standing 100ft away, and we both wear blindfolds, we'll both record different times based on the sound.

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another are I have jsut thougth of that may lead SRt astray is that even if a GPS has supposedly got >V than a surface clock it's orbit may actually be slower than that of the surface due to the movement of teh solar system within the galactic ballet.

In other words the illusion of greater velocity could give totally wrong dilation results.

How fast is the Earth travelling contra to the GPS orbit?

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No. All that matters is the relative velocity between observers. The solar system could be spinning wildly through the galaxy (hmmm... I guess it is...) and it makes no difference to the measurements between ourselves and a sat in a stable orbit.

All of your statements so far have an underlying assumption of some reference other than the frames you are talking about. This gets you nowhere.

At some point you just have to accept that there is no absolute reference and no absolute "reality" or "truth" as proven by experiments which match theory exquisitely. As the observer, truth is what you say it is. And if you switch your POV, truth switches with you.

Pete you raise a couple of very interesting and quite rational points. I will diogest and post some more

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Good, and I'm waiting with anticipation!

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Pete said:

The observer on a ship can't assume they're stationary relative to the other ship, of course. They can, however, use a model (like SRT) to predict what things look like from that other ship's perspective. In other words, they can answer the question "What if I were stationary w.r.t. the other ship?" Or "What if I were heading in direction x at y m/s?"

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This makes a lot of sense except that the pulses are not subject to prediction.

They, like the tree just are what they are.

We may like to use the "IF" factor but the light pulses are happening as they naturally do regardless of the "IF" factor.

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Of course! But what the observer sees is subject to the "IF" factor. IF the observer had different motion, they would observe things differently, yes?

It just occurred to me that perhaps you haven't thought about relativity from the perspective of being a change to the observer rather than the other way around (fundamentally, it's not either... but it helps to think about it in that way at some stage).

Pete and others, I think we need to establish the very first concept.
The following simple diagram shows two objects.
They are the only two objects in this imaginary universe.
The only thing we know is that they have a closing velocity of 0.8c.

Simple question:

Which is moving?
A or B or Both or neither

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Movement is relative, just like "here" is relative.
Imagine there is a tree on A.

Where is the tree? Here or There?

A says "here", and is correct.
B says "there", and is correct.

So which is the real truth? Is the tree Here or There???

The problem with your animated image is that you have explicitly specified that A and B are both moving against some fixed background. This is a natural intuitive position - you are imagining some type of "Ether"... some fixed background that forms an absolute rest frame.

The difficulty is that the fixed background is undectable if it exists at all! So SRT simply suggests that it doesn't exist, and finds a consistent model without it.

Another way of approaching your animated image is to imagine that the backdrop is infinite... if it's infinite, can you tell if its moving? The moving "window" you've placed on the backdrop is arbitrary... you could just as easily have reversed the window's movement, right?

According to C object A and C1 are co-moving and objects B and C2 are also co-moving.

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[ Edit - Please ignore the following two lines. Thanks to superluminal for pointing out my silly error. ]

Please!! That's not what comoving means!
Comoving means stationary with respect to each other.​

Object A according to SRT will state that object B has all the velocity thus his light pulses on his reflector [remember the two ship scenario posted earlier] will be out of phase.

Now clearly there is a conflict between what C knows as true and A and B know as true.

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Not so! I explained this already. If A and B are approaching each other at 0.8c (in A's frame or B's frame), then A will receive B's pulses 3 times faster than A sends pulses. This is true in ALL reference frames. A, B, and C all agree on this!

The interpretation they each make of this (the original pulse rates) will be different, but that's OK - the original rates are relative measures, just like "here" and "there".

Actually Pete this is a good example of how easy it is to be mistaken on the internet.
Originally I made a mistake with the statement that they were at rest. SL corrected me and said they were co-moving [two ships at equal v coming towards each other] And then I used this error later which you corrected me on, That they were not co-moving and so I corrected for the last diagram but you had failed to see my correction.....sheesh!!! What fun we have.....ha

Pete's right. All are correct. Each is correct in his own reference frame. Nobody has a "privileged" view of what's going on.

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JamesR, Thanks for your response and I agree that this would be the SRT position.
However and there is always a however, I would question the merit of a theory that allows C to observe A as being in synch with B yet A observes that he is not in synch with B.

Just to make my hesitation very clear:

C sees A is in Synch with B
A sees he is out of synch with B

So maybe instead of claiming all views are correct we should be claiming all views are Incorrect.

edit: keeping in mind that what C sees is what A sends to him to see. [light pulses] C gets a light signal that tells him that A and B are in Synch according to A. Yet simultaneously A is also claiming that he is out of synch with B.

Intuitively one would have to consider that there is a problem....With the fact that A is stating he has two observations. To me it demonstrates a hard syntax error in how we are applying SRT to this scenario.

By 'one', are you referring to us as independent analysts, or the observer on a ship?
The observer on a ship can't assume they're stationary relative to the other ship, of course. They can, however, use a model (like SRT) to predict what things look like from that other ship's perspective. In other words, they can answer the question "What if I were stationary w.r.t. the other ship?" Or "What if I were heading in direction x at y m/s?"

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Ther distinction between a prediction and an observation needs to be brought to the fore here.

IN the scenario I showed two ships coming together at v=0.8c. There are no other references to draw upon. You have stated that whilst hey ca not assume their v is relative zero, they can use the SRT model to predict what the othership will see and to do so it has to be assumed that one has all the velocity. This is s bit of a logic loop or circular reasoning....IMO

Can't asssume he is at rest but must do so to predict what the other is seeing......circular for sure.....

The issue is not about prediction but more about inherant symmetry when two ships are approaching each other and they are considered the only two objects in their universe. Whilst each frame is at rest to itself this does not mean that the ships rest frame is at rest relative to the other ship.

The other thing:

I accept your prediction, but I'd like to restrict our discussion to what the predictions of SRT are, and whether they are internally consistent; i.e. whether there is any situation in which one can correctly apply SRT in two different reference frames and produce two different predictions of what an observer actually sees. (If such a situation exists, then this disproves SR.)

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Whilst my debate is essentially about just this, I am not in any way attempting to disprove SRT. I accept that SRT will stand or fail on it's own merit.

What I am interested in is how SRT deals with what is apparently an inconsistancy in that in the case of our scenario A's observation is one for himself and one for C. when both observations are generated by A.

IN the scenario I showed two ships coming together at v=0.8c. There are no other references to draw upon. You have stated that whilst hey can not assume their v is relative zero, they can use the SRT model to predict what the othership will see and to do so it has to be assumed that one has all the velocity. This is s bit of a logic loop or circular reasoning....IMO

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Actually, neither observer can draw on the other ship's velocity as a direct observation. They can only predict what that velocity is based on their observations.

They can use any model and data they want to predict what the othership observes, but only a good model together with good data will give predictions that correspond to the actual observations of the othership.

If an observer assumes that they have a velocity of zero relative to the othership, then they're working with bad data, so their predictions will not give good results.

Can't asssume he is at rest but must do so to predict what the other is seeing......circular for sure.....

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He can assume he is at rest. In fact he must, with no other reference to go by. He can't assume he is at rest relative to the othership.

Whilst my debate is essentially about just this, I am not in any way attempting to disprove SRT. I accept that SRT will stand or fail on it's own merit.

What I am interested in is how SRT deals with what is apparently an inconsistancy in that in the case of our scenario A's observation is one for himself and one for C. when both observations are generated by A.

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If you find a true inconsistency, then this disproves SR. Part of 'standing on it's own merit' is producing consistent results.

Do you accept that the prediction of SR is that A observes B's pulses arrive three times faster than A's pulses leave, and that this prediction is consistent in all frames?

You might wonder what I'd personally consider to be a "true inconsistency".

Well, I have something I borrowed from Schrodinger called "the classical cat test".

If it is possible to describe valid initial conditions including a cat, such that two valid applications of some model are inconsistent in their prediction of the cat's fate, then a true inconsistency has been discovered and the model in question can not correspond to reality.​

For example, place a cat in ship A together with some lethal apparatus triggered by some sort of detector. If some observer validly uses SRT to predict that the apparatus will fire and the cat dies, while some other observer validly uses SRT to predict that the apparatus will not fire, then SRT is shown to be truly inconsistent.

Note that this test is a classical test - I don't attempt to apply it to quantum models.